Any decent web browser* has the ability to install additional features. One example feature is an ‘ad blocker’: something that looks at each page and removes things it thinks are ads so that the user doesn’t see them. As this greatly improves the user’s experience – when I have to use a browser without one, I am horrified by what some sites look like with ads – it is a very common thing to do.
Because there is currently no easy way for the ad blocker to determine whether something is an unwanted ad or wanted content by looking at an image itself**, they go by the URL of the item.
Some are easy: you probably don’t want anything at all from doubleclick.com or from a directory called /ads/, for example. Others are harder, but the name of the file can also be a clue.
A YES client recently wondered why some people couldn’t see her banners on another site. It turned out that name of the banner ad image file contained the string ‘468×60’. As 468 pixels*** wide by 60 pixels high is a very popular size for banner ads, the filters that one very common ad blocker uses includes looking for this string and, if it finds it, the ad blocker ensures that the user doesn’t see the file. Oops. As soon as it was renamed, all was fine…
.. on that site, anyway. It turns out that a popular escort directory shows the banner ads that people have paid £££s for in a way that leads the lot of them being blocked by any decent filter. Oops.
Moral: install an ad blocker – ‘AdBlock Plus’ is the most popular – and see what’s happening to your ads.
* This may well exclude even modern versions of Internet Explorer. Certainly all the versions I have aren’t. Think Firefox / Iceweasel, Chrome / Chromium, Opera, or I think Safari as included in ‘decent’.
** This is why people who demand that internet companies block everything they don’t personally like are technically illiterate. Blocking text stuff is one thing, even if people who want to get around the block will just start using other words, but trying to automatically categorise pictures and videos is Very Hard.
*** A pixel is the smallest element that makes up a picture or video, a dot of colour (only one at any one time). Normally, they appear so small on the screen that you can’t notice them individually. Vendors love to sell cameras on how many the pictures have, but this actually one of the less important things to look for when buying one.